Electrochemical measuring devices have been commonly used to determine the concentration of analytes in body fluids. For example, in blood-glucose testing, the test strip may be inserted into a glucose meter, and then a blood sample may be dropped at a measuring end of a test strip that is applied with an enzyme to determine the concentration of glucose in the blood sample.
In the conventional art, the test strip is provided with a working electrode and a reference electrode to form a reaction region. The reaction region is applied with the enzyme so that when a test sample reacts with the enzyme, a chemical response is generated. When in use, the test strip is inserted in the glucose meter so that the glucose meter can read the chemical response in order to calculate the concentration of glucose in the blood sample.
However, as a result of variances in manufacturing of the test strips, calibration is needed before a particular batch of the test strips may be used with the glucose meter to obtain accurate test results. In the conventional art, the test strips are provided with a number of contact pads. These contact pads are used to couple with metal pins provided on a semiconductor chip within the glucose meters to generate electrical current, which in turn produces electrical responses readable by the glucose meters. To compensate for the manufacturing variations, the contact pads on the test strips are encoded with calibration information that may be assigned for use in computing the test results.
One common problem in the conventional art is the amount of coding information that can be encoded in the contact pads for calibration purpose. As an example, a chip with eight pins provided within the conventional glucose meter can correspond to a test strip with eight contact pads. A common arrangement of the eight contact pads may be 2 rows of 4 contact pads at one end of any given test strip. In the conventional art, there are at least a working electrode and a reference electrode to connect with contact pads. Then, depending on the status of electrical conductivity between any contact pads and common pad well know by the art, a logic value of 1 or 0 is assigned, thereby yielding a maximum of 32 (=25) codes to be used for auto-calibration purpose. Such limitation hinders the optimal use of the glucose meter and test strips.
Therefore, what is needed is a method of increasing the number of auto-calibration codes without changing the existing structure and configuration of the glucose meter and the test strip and device for same.
What is also needed is a method of verifying the auto-calibration codes to increase the accuracy when using the glucose meter in combination with the test strip.